Lighting Control

ABSTRACT

A method in a lighting system includes a lighting system control entity and a plurality of luminaires wirelessly coupled to the lighting system control entity. The method includes controlling light output of a respective luminaire in accordance with a preprogrammed lighting control logic that defines switching on the light output in response to detecting occupancy at the respective luminaire, transmitting status indications to and receiving status indications from other luminaires, deriving relationship data including one or more relationship strength values, each pertaining to a particular other luminaire and being descriptive of an extent of regularity at which reception of a status indication that indicates an occurrence of a given event pertaining to the particular luminaire is followed by detecting occupancy at the respective luminaire, and transmitting the relationship data to the lighting system control entity. The method includes controlling an aspect of operational dependencies among the luminaires in accordance with the relationship data.

TECHNICAL FIELD

The present invention relates to control of light output of luminairesoperating as part of a lighting system based on sensor data captured atthe luminaires.

BACKGROUND

Many lighting systems applied for illuminating an indoor space and/or anoutdoor space involve usage of luminaires that are able to autonomouslycontrol at least some aspects of their operation based on environmentalcharacteristics determined via usage of one or more sensors provided inthe space. Typical, but non-limiting, examples of sensors applicable forat least partially controlling the light output from luminaires of alighting system include an occupancy sensor and a light sensor: whileoccupancy sensors may be applied to switch lights on in response todetecting occupancy in the illuminated space and to switch lights off inresponse to detecting non-occupancy in the illuminated space, lightsensors may be applied to control the light output in view of theambient light in the space such that a desired level of illumination isprovided. Hence, occupancy sensors and light sensors enable at leastpartially autonomous lighting control that ensures user comfort whileminimizing energy consumption.

Sensors applied for controlling light output of a luminaire may bearranged in a sensor unit or a sensor portion provided in the luminaire,whereas respective sensor signals obtained from sensors of such anintegrated sensor unit may be applied for controlling respective lightoutput of the luminaire. Moreover, two or more such luminaires providedwith integrated sensor units may be arranged into a luminaire group,where a certain luminaire of the group may control some aspects of itslight output based on sensor data captured at other luminaires of thesame luminaire group and/or based on operational statuses of the otherluminaires of the luminaire group. An example of such group-basedlighting control includes switching on or keeping on the light output ofthe certain luminaire in case of sensor data captured at anotherluminaire in the same luminaire group indicating occupancy and/orswitching on or keeping on its light output even if the sensor dataacquired at the certain luminaire does not indicate occupancy, whereasin another example the group-based lighting control may involve thecertain luminaire switching off its light output (e.g. via applicationof a shortened dimming curve) in case of respective sensor data capturedat all luminaires of the luminaire group indicates non-occupancy.

To enable such group-based lighting control at a certain luminaire, thecertain luminaire needs to have knowledge of the other luminairesassigned to the same luminaire group with the certain luminaire andinformation of lighting control actions (e.g. switching or keeping thelight output on or off) taken at other luminaires of the luminairegroup. Such information may be acquired via the luminaires of thelighting system transmitting (e.g. broadcasting) messages that includeinformation of sensor data captured therein and/or information onlighting control actions taken thereat to other luminaires of thelighting system via a lighting control network that connects theluminaires of the lighting system to each other.

Luminaire grouping may be useful, for example, to ensure sufficientlighting at and close to locations where occupancy is detected and/or toensure substantially uniform lighting from multiple luminaires that arerelatively close to each other in the same space (e.g. in the sameroom). In a traditional lighting system design the information thatdefines any luminaire groups applied therein is manually preconfiguredinto the luminaires upon installing, configuring or reconfiguring thelighting system to enable the group-based lighting control. However,especially in large lighting systems manual configuration of theluminaires to enable the group-based lighting control constitutes asignificant effort while the manual configuration procedure is alsoprone to errors and hence advanced approaches in this regard are highlydesirable.

SUMMARY

It is an object of the present invention to provide an approach forautomated or semi-automated determination of luminaire groups for alighting system.

According to an example embodiment, a lighting system comprising alighting system control entity and a plurality of luminaires that arewirelessly coupled to the lighting system control entity is provided,wherein a luminaire of the plurality of luminaries comprises: aluminaire control portion arranged to control light output of therespective luminaire in accordance with a preprogrammed lighting controllogic that defines switching on the light output in response todetecting occupancy at the respective luminaire, and transmit statusindications to and receive status indications from other ones of theplurality of luminaires, wherein each status indication is descriptiveof an occurrence of an event pertaining to a luminaire transmitting therespective status indication; and an adaptation portion arranged toderive relationship data including one or more relationship strengthvalues, wherein each relationship strength value pertains to aparticular other luminaire of said plurality of luminaires and isdescriptive of an extent of regularity at which reception of a statusindication that indicates an occurrence of a given event pertaining tothe particular other luminaire is followed by detecting occupancy at therespective luminaire, and transmit the relationship data to the lightingsystem control entity; and wherein the lighting system control entitycomprises a control portion arranged to control at least one aspect ofoperational dependencies among the plurality of luminaires in accordancewith the relationship data received from the plurality of luminaires.

According to another example embodiment, a method in a lighting systemcomprising a lighting system control entity and a plurality ofluminaires that are wirelessly coupled to the lighting system controlentity is provided, wherein the method comprises, in a luminaire of theplurality of luminaires, controlling light output of the respectiveluminaire in accordance with a preprogrammed lighting control logic thatdefines switching on the light output in response to detecting occupancyat the respective luminaire, transmitting status indications to andreceiving status indications from other ones of the plurality ofluminaires, wherein each status indication is descriptive of anoccurrence of an event pertaining to a luminaire transmitting therespective status indication, deriving relationship data including oneor more relationship strength values, wherein each relationship strengthvalue pertains to a particular other luminaire of said plurality ofluminaires and is descriptive of an extent of regularity at whichreception of a status indication that indicates an occurrence of a givenevent pertaining to the particular other luminaire is followed bydetecting occupancy at the respective luminaire, and transmitting therelationship data to the lighting system control entity; and wherein themethod comprises, in the lighting system control entity, controlling atleast one aspect of operational dependencies among the plurality ofluminaires in accordance with the relationship data received from theplurality of luminaires.

According to another example embodiment, a computer program is provided,the computer program comprising computer readable program codeconfigured to cause performing at least a method according to an exampleembodiment described in the foregoing when said program code is executedon one or more computing apparatuses.

The computer program according to the above-described example embodimentmay be embodied on a volatile or a non-volatile computer-readable recordmedium, for example as a computer program product comprising at leastone computer readable non-transitory medium having the program codestored thereon, which, when executed by one or more computingapparatuses, causes the computing apparatuses at least to perform themethod according to the example embodiment described in the foregoing.

The exemplifying embodiments of the invention presented in this patentapplication are not to be interpreted to pose limitations to theapplicability of the appended claims. The verb “to comprise” and itsderivatives are used in this patent application as an open limitationthat does not exclude the existence of also unrecited features. Thefeatures described in the following examples may be used in combinationsother than those explicitly described, unless explicitly statedotherwise.

Some features of the invention are set forth in the appended claims.Aspects of the invention, however, both as to its construction and itsmethod of operation, together with additional objects and advantagesthereof, will be best understood from the following description of someexample embodiments when read in connection with the accompanyingdrawings.

BRIEF DESCRIPTION OF FIGURES

The embodiments of the invention are illustrated by way of example, andnot by way of limitation, in the figures of the accompanying drawings,where

FIG. 1 illustrates a block diagram of some logical components of alighting system according to an example;

FIG. 2 illustrates a block diagram of some components of a luminaireaccording to an example;

FIG. 3 illustrates a block diagram of some components of a lightingsystem gateway according to an example;

FIG. 4 illustrates a block diagram of some logical components of alighting system server according to an example;

FIG. 5 illustrates a method according to an example; and

FIG. 6 illustrates a block diagram of some components of an apparatusaccording to an example.

DESCRIPTION OF SOME EMBODIMENTS

FIG. 1 illustrates a block diagram of some components of a lightingsystem 100 according to an example. The lighting system 100 may bearranged for illuminating a space or area, which may comprise e.g. oneor more indoor spaces or areas and/or one or more outdoor spaces orareas. In the following, for brevity of description, the space or areathat the lighting system 100 serves to illuminate is referred to as anilluminated space.

In the example of FIG. 1 the lighting system 100 is shown withluminaires 120-1, 120-2, 120-3 and 120-4, a lighting system gateway 140and a lighting system server 150. The luminaires 120-1 to 120-4represent a plurality of luminaires 120, whereas any individualluminaire may be referred to via a reference number 120-k. The pluralityof luminaires 120 are arranged for illuminating respective locations ofthe illuminated space. In this regard, it is worth noting that theexample of FIG. 1 serves to illustrate the plurality of luminaires 120,the lighting system gateway 140 and the lighting system server 150 asrespective elements of the lighting system 100, while on the other handthe illustration of FIG. 1 does not serve to illustrate any physicalcharacteristics of these elements of the lighting system 100 and/orspatial relationship between these elements of the lighting system 100.

The plurality of luminaires 120 and the lighting system gateway 140 maybe communicatively coupled to each other via respective wirelesscommunication links or via a wireless communication network providedusing a suitable wireless communication technique known in the art, eachof the plurality of luminaires 120 and the lighting system gateway 140hence serving as a respective node of a lighting control network. Thelighting system gateway 140 may be communicatively coupled to thelighting system server 150 via a wireless or wired communication link orcommunication network to enable transfer of information between thelighting system gateway 140 and the lighting system server 150.

FIG. 2 illustrates a block diagram of some (logical) components of aluminaire 120-k according to an example. In the following, variouscharacteristic of structure and operation of any of the plurality ofluminaires 120 are described via references to the single luminaire120-k, whereas these characteristics pertain to each of the plurality ofluminaries 120, unless explicitly described otherwise. The luminaire120-k may comprise at least one light source 121-k for providing lightoutput of the luminaire 120-k, a sensor portion 122-k for observingenvironmental characteristics at a location illuminated by the luminaire120-k, a communication portion 123-k for wireless communication withother elements of the lighting control network, a luminaire controlportion 124-k for controlling at least one aspect of operation of theluminaire 120-k and an adaptation portion 125-k for adjusting operationof the control portion 124-k in accordance with its operatingenvironment. The luminaire control portion 124-k and the adaptationportion 125-k may constitute, at least conceptually, a luminaire controlapparatus 126-k.

According to an example, the at least one light source 121-k maycomprise one or more light emitting diodes (LEDs) and the luminairecontrol portion 124-k may comprise or it may be provided as a LED driverdevice, whereas in another non-limiting example the at least one lightsource 121-k may comprise one or more fluorescent lamps and theluminaire control portion 124-k may comprise or it may be provided as anelectronic ballast.

The sensor portion 122-k may comprise one or more sensors arranged toobserve respective environmental characteristics at the location of theluminaire 120-k. The one or more sensors of the sensor portion 122-k maybe communicatively coupled, e.g. via respective electrical wires, to theluminaire control portion 124-k in order to provide respective sensorsignals thereto. The one or more sensors of the sensor portion 122-k maycomprise e.g. one or more of the following:

-   -   an occupancy sensor for monitoring occupancy at the location of        the sensor luminaire 120-k, e.g. a passive infrared (PIR)        sensor, a microwave radar, a lidar, etc.;    -   a light sensor for measuring ambient light level at the location        of the luminaire 120-k, e.g. photodetector such as photodiode;    -   a temperature sensor for measuring ambient temperature at the        location of the luminaire 120-k;    -   a humidity sensor for measuring air humidity at the location of        the luminaire 120-k;    -   a carbon dioxide (CO₂) sensor for measuring a CO₂ level at the        location of the luminaire 120-k;    -   a volatile organic compound (VOC) sensor for measuring        respective levels of one or more VOCs at the location of the        luminaire 120-k.

The sensor data conveyed via the sensor signals from the sensor portion122-k to the luminaire control portion 124-k may be referred to as localsensor data due to its local availability in the luminaire 120-k,whereas the local sensor data or a portion thereof may be applied by theluminaire control portion 124-k for controlling the light output of theluminaire 120-k.

Along the lines described in the foregoing, the communication portion123-k may enable wireless communication with other elements of thelighting control network. In this regard, the communication portion123-k may comprise a respective communication apparatus, e.g. a wirelesstransceiver, that is capable of communicating with respectivecommunication apparatuses provided in other elements of the lightingcontrol network using one or more predefined wireless communicationtechniques or protocols. The wireless communication may be carried outvia using a suitable short-range wireless communication technique knownin the art that enables communication over ranges from a few meters upto a few hundred meters. Examples of suitable short-range wirelesscommunication techniques include Bluetooth, Bluetooth

Low-Energy (BLE), ZigBee, WLAN/Wi-Fi according to an IEEE 802.11 familyof standards, etc. The choice of the wireless communication techniqueand network topology applied for a specific implementation of thelighting control network may depend e.g. on the required communicationrange and/or requirements with respect to energy-efficiency of thecommunication apparatuses.

The luminaire control portion 124-k may control one or more aspects oflight output of the at least one light source 121-k in accordance withthe local sensor data obtained from the sensor portion 122-k and/or inaccordance with status information received via the communicationportion 123-k from one or more other luminaires of the lighting system100. In an example, the luminaire 120-k may comprise an apparatuscomprising a processor and a memory, where the memory is arranged tostore computer program code that, when executed by the processor, causesthe apparatus to operate as the luminaire control apparatus 126-k,thereby providing respective operations of the luminaire control portion124-k and the adaptation control portion 125-k according to the presentdisclosure. More detailed examples of using the processor and the memoryfor implementing the luminaire control portion 124-k are described laterin this text with references to FIG. 6 .

The luminaire 120-k or an element thereof may have a device ID, e.g. anaddress, a serial number, a name, etc. assigned thereto. The device IDassigned to the luminaire 120-k may be referred to as a luminaire ID ofthe luminaire 120-k. The luminaire ID may be stored, for example, in thememory provided in the luminaire 120-k and it may be applied, forexample, to identify the respective luminaire 120-k in communicationbetween elements of the lighting control network.

Along the lines described in the foregoing, the luminaire controlportion 124-k may control one or more aspects of light output of the atleast one light source 121-k in accordance with the local sensor dataobtained from the sensor portion 122-k. In the course of its operation,the luminaire control portion 124-k may record or derive sensorindications based on respective sensor signals received from the sensorportion 122-k, which may be referred to as local sensor indicationssince they are based on sensor data captured locally at the luminaire120-k. The luminaire control portion 124-k may arrange the local sensorindications into a respective time series of local sensor indications.Examples in this regard include deriving local occupancy stateindications (i.e. respective indications of one of occupancy ornon-occupancy) based on an occupancy sensor signal received from anoccupancy sensor of the sensor portion 122-k and/or deriving local lightlevel indications based on a light sensor signal received from a lightsensor of the sensor portion 122-k. Consequently, the light output ofluminaire 120-k may be controlled based at least in part on one or moretime series of local sensor indications, e.g. on a time series of localoccupancy state indications and/or on a time series of local light levelindications.

The luminaire control portion 124-k may apply a preprogrammed lightingcontrol logic that defines controlling the light output of the luminaire120-k in accordance with the sensor data obtained from the sensorportion 122-k. As an example, the preprogrammed lighting control logicmay define switching on the light output of the luminaire 120-k as aresponse to the local sensor data indicating occupancy (after a periodof non-occupancy) and define switching off the light output of theluminaire 120-k as a response to the local sensor data

indicating non-occupancy (after a period of occupancy). In this regard,the preprogrammed lighting control logic may include one or morepredefined lighting control rules, where each lighting control rule maydefine a respective pair of a triggering condition and a lightingcontrol action to be carried out as a response to an occurrence of thetriggering condition, where the triggering condition may directly orindirectly pertain to one or more time series of local sensorindications. As a non-limiting example, the preprogrammed lightingcontrol logic may define one or more of the following lighting controlrules:

-   -   a first lighting control rule that defines switching on the        light output of the luminaire 120-k to a predefined target light        intensity or otherwise adjusting the light output of the        luminaire 120-k from a lower light intensity to the predefined        target light intensity as a response to the time series of local        occupancy indications indicating a change of the occupancy state        from non-occupancy to occupancy;    -   a second lighting control rule that defines adjusting the light        output of the luminaire 120-k (e.g. from the predefined target        light intensity) to a predefined stand-by light intensity (e.g.        switching off the light output of the luminaire 120-k) in        accordance with a predefined dimming curve as a response to the        time series of local occupancy indications indicating a change        of occupancy state from occupancy to non-occupancy;    -   a third lighting control rule that defines increasing the light        intensity applied for the light output of the luminaire 120-k as        a response to the time series of local light level indications        indicating a light level that is below a target light level by        more than a predefined margin;    -   a fourth lighting control rule that defines decreasing the light        intensity applied for the light output of the luminaire 120-k as        a response to the time series of local light level indications        indicating a light level that is above the target light level by        more than the predefined margin.

The target light intensity, the stand-by light intensity, the targetlight level and the predefined margin referred to above are predefinedlighting control parameters that may be set to respective predefinedvalues e.g. upon manufacturing, installing, configuring or reconfiguringthe luminaire 120-k. The predefined dimming curve referred to above maydefine adjustment of the light output from the predefined target lightintensity to the stand-by lighting intensity via one or more predefinedintermediate light intensities over a predefined dimming period, whereparameters that characterize the predefined dimming curve (e.g. theintermediate light intensities and duration of the dimming period) maybe likewise set upon manufacturing, installing, configuring orreconfiguring the luminaire 120-k. Moreover, to account for scenarioswhere the occupancy state remains unchanged, the preprogrammed lightingcontrol logic may comprise respective lighting control rules for keepingon the light output of the luminaire 120-k as a response to the timeseries of local occupancy indications indicating continued occupancyand/or for keeping off the light output of the luminaire 120-k as aresponse to the time series of local occupancy indications indicatingcontinued non-occupancy.

The luminaire control portion 124-k may further operate thecommunication portion 122-k to transmit (e.g. broadcast) statusindication messages from the luminaire 120-k to the other nodes of thelighting control network. A status indication message may comprise oneor more status indications that are descriptive of an aspect ofoperational status of the luminaire 120-k, e.g. descriptive of anoccurrence of an event pertaining to the luminaire 120-k such aslighting control actions taken by the luminaire 120-k and/or the localsensor indications recorded or derived in the luminaire control portion124-k.

Conversely, the luminaire control portion 124-k may receive, via thecommunication portion 123-k, status indication messages (and hencestatus indications) from other ones of the plurality of luminaires 120.In this regard, a status indication transmitted from the luminaire 120-kmay comprise e.g. an action indication that identifies a lightingcontrol action taken at the luminaire 120-k or a sensor data indicationthat reports a current (or the most recent) sensor indication recordedor derived at the luminaire control portion 124-k. Non-limiting examplesof action indications and sensor data indications include the following:

-   -   a first action indication that indicates switching on the light        output of the luminaire 120-k (to be transmitted e.g. due to a        change of the occupancy state from non-occupancy to occupancy        detected at the luminaire 120-k),    -   a second action indication that indicates initiating adjustment        of the light output of the luminaire 120-k to the stand-by light        intensity (to be transmitted e.g. due to a change in the        occupancy state from occupancy to non-occupancy detected at the        luminaire 120-k),    -   a third action indication that indicates keeping on the light        output of the luminaire 120-k (to be transmitted e.g. due to        continued occupancy detected at the luminaire 120-k),    -   a fourth action indication that indicates keeping the light        output of the luminaire 120-k at the stand-by light intensity        (to be transmitted e.g. due to continued non-occupancy detected        at the luminaire 120-k);    -   an occupancy sensor data indication reporting the current (or        the most recent) local occupancy state indication recorded or        derived at the luminaire 120-k,    -   a light sensor data indication reporting the current (or the        most recent) local light level indication recorded or derived at        the luminaire 120-k.

A status indication message may further comprise the luminaire IDassigned to the luminaire 120-k transmitting the status indicationmessage, thereby providing an identification of the luminaire 120-k towhich the status indication(s) conveyed in the status indication messagepertain.

In the course of operation of the luminaire, the adaptation portion125-k may store, in the memory provided in the luminaire 120-k, historydata that records a history of application of the one or more lightingcontrol rules of the preprogrammed lighting control logic by theluminaire control portion 124-k. In this regard, the history data maycomprise a history of occurrences of triggering conditions and theresulting lighting control actions the luminaire control portion 124-khas taken as a response to the triggering conditions and a history ofstatus indications received from other ones of the plurality luminaires120 via the lighting control network. Moreover, the history data storedby the adaption portion 125-k may further include a history of statusindications transmitted from the luminaire 120-k and possibly also ahistory of local sensor indications recorded or derived at the controlportion 124-k. Each piece of history data may be stored together withrespective timing information that indicates the capturing time and/orthe transmission time of a respective piece of stored data (whicheverapplies). The timing information may comprise a respective timestampthat indicates time with respect to a predefined reference time.

The adaptation portion 125-k may carry out a learning procedure via ananalysis of the history data captured during an analysis period, e.g.during an a past time period of a predefined duration that precedes theanalysis. In various examples, the analysis period may cover a periodhaving a duration from a few minutes to a few weeks, depending on thesize of the lighting system 100 and/or characteristics of the space thelighting system 100 serves to illuminate. The analysis may aim atdetermining an extent of operational relationship between the luminaire120-k and one or more other ones of the plurality of luminaires 120. Inan example, the analysis with respect to a particular other luminaire120-p may involve deriving a respective relationship strength value thatis descriptive of an extent of regularity at which detecting anoccurrence of a given event pertaining to the particular other luminaire120-p (e.g. detecting occupancy at the location of the particular otherluminaire 120-p) is followed by detecting occupancy at the location ofthe luminaire 120-k, where detecting occupancy may comprise detecting achange in the occupancy state at the respective location fromnon-occupancy to occupancy. Such operational similarity between theluminaire 120-k and the particular other luminaire 120-p may beconsidered as an indication of the luminaire 120-k and the particularother luminaire 120-p operating in a relatively close proximity to eachother and hence serving to illuminate portions of the space that orrelatively close to each other and/or that are relatively closely linkedto each other in terms of movement of occupants of the space.

In an example, the learning procedure may involve the adaptation portion125-k carrying out the analysis with respect to one or more other onesof the plurality of luminaires in order to derive the respectiverelationship strength value for the one or more other ones of theplurality of luminaires 120, where the relationship strength value thatpertains to the particular other luminaire 120-p may be descriptive ofan extent of regularity at which reception of a status indication thatindicates an occurrence of the given event that pertains to (operationof) the particular other luminaire 120-p is followed by detection ofoccupancy at the location of the luminaire 120-k. As an example in thisregard, the given event that pertains to the (operation of) theparticular other luminaire 120-p may comprise one that is at leastindirectly indicative of detection of a change in occupancy state fromnon-occupancy to occupancy at the location of the particular otherluminaire 120-p, whereas detection of an occurrence of the given eventhaving occurred at the particular other luminaire 120-p may comprisee.g. the luminaire 120-k receiving a given status indication from theparticular other luminaire 120-p. Moreover, detection of occupancy atthe location of the luminaire 120-k may comprise e.g. identifying achange from non-occupancy to occupancy based on the time series of localoccupancy indications recorded or derived at the luminaire controlportion 124-k.

In an example, the given status indication that may be considered inderivation of the relationship strength value may be one that at leastindirectly indicates a change from non-occupancy to occupancy observedat the particular other luminaire 120-p, e.g. one of the following:

-   -   an action indication that indicates switching on the light        output of the particular other luminaire 120-p, e.g. the first        action indication described in the foregoing,    -   an occupancy sensor data indication that indicates a change of        occupancy state from non-occupancy to occupancy detected at the        particular other luminaire 120-p.

The luminaire control portion 124-k may operate the communicationportion 123-k to transmit the relationship strength values derived bythe adaptation portion 125-k via the lighting system gateway 140 to thelighting system server 150. This information may be transmitted from theluminaire 120-k to the lighting system server 150 as relationship data,which may include the respective relationship strength values for one ormore other ones of the plurality of luminaries 120 and luminaire IDs ofthe respective luminaries. The relationship data may include furtherinformation pertaining to one or more other luminaires of the pluralityof luminaires 120 derived at the luminaire 120-k (as described in moredetail via examples provided in the following).

Along the lines described in the foregoing, the relationship strengthvalue pertaining to the particular other luminaire 120-p may be based onthe history data, e.g. on the local occupancy indications recorded inthe history data and on occasions of receiving the certain statusindication originating from the particular other luminaire 120-precorded in the history data. In this regard, the relationship strengthvalue that pertains the particular other luminaire 120-p and that isderived based on occasions of receiving the given status indication fromthe particular other luminaire 120-p may be derived in various ways, asfar as it serves its purpose of indicating the extent of regularity atwhich reception of the given status indication from the particular otherluminaire 120-p is followed by detection of occupancy at the location ofthe luminaire 120-k In this regard, a straightforward example forderiving the relationship strength value pertaining to the particularother luminaire 120-p at the luminaire 120-k is described in thefollowing in order to illustrate certain exemplifying characteristics ofthe relationship strength values according to the present disclosure,whereas a more sophisticated non-limiting example regarding derivationof the relationship strength values is provided in paragraphs [0032] to[0056] of European patent publication no. 3171674 A1.

In general, in order to exhibit some extent of operational relationshipbetween the luminaire 120-k and the particular other luminaire 120-parising from these two luminaires operating in relatively closeproximity of each other, detection of occupancy at the location of theluminaire 120-k typically follows reception of the given statusindication from the particular other luminaire 120-p within a timewindow of certain duration. In this regard, depending on characteristicsof operating environment of the lighting system 100, the time window mayhave a duration in a range from a few tenths of a second to a few tensof seconds. Consequently, a straightforward example to illustratederivation and characteristics of the relationship strength valuepertaining to the particular other luminaire 120-p may involve

-   -   determining N_(all) as the number of all occasions of receiving        the given status indication from the particular other luminaire        120-p during the analysis period,    -   determining N_(flw) as the number of those occasions of        receiving the given status indication from the particular other        luminaire 120-p during the analysis period that are followed by        detection of occupancy at the location of the luminaire 120-k        within the time window of certain duration,    -   deriving the relationship strength value based on a ratio of        N_(flw) to N_(all).

In an example, the relationship strength value may be derived directlyas the ratio of N_(flw) to N_(all), whereas in another example therelationship strength value may be derived as the ratio of N_(flw) toN_(all) further adjusted based on observed time margins betweenreception of the given status indication from the particular otherluminaire 120-p and detection of occupancy at the location of theluminaire 120-k in different occasions of such a sequence of eventsoccurring with the time window of the certain duration. An effect of theobserved time margins to the resulting relationship strength value mayinclude e.g. one or more of the following:

-   -   the relationship strength value may increase with decreasing        representative time margin and the relationship strength value        may decrease with increasing representative time margin, where        the representative time margin may be e.g. an average or median        of observed time margins,    -   the relationship strength value may increase with decreasing        variance of observed time margins and the relationship strength        may decrease with increasing variance of observed time margins.

Without losing generality, the relationship strength value may beconsidered as a value that is normalized into a predefined range thatcovers values from a predefined minimum value (e.g. zero) to apredefined maximum value (e.g. one), where a larger value indicates ahigher extent of operational relationship between the luminaire 120-kand the particular other luminaire 120-p.

According to an example, in addition to delivering the relationshipstrength values in the relationship data from the luminaire 120-k viathe lighting system gateway 140 to the lighting system server 150, theadaptation portion 125-k may adjust some aspects of lighting controlapplied by the luminaire control portion 124-k based on the relationshipstrength values. Such adaptation of operation of the luminaire controlportion 124-k may be provided via the adaptation portion 125-k carryingout a first reprogramming procedure, which may involve supplementing thefirst preprogrammed lighting control logic of the luminaire controlportion 124-k in accordance with the respective relationship strengthvalues derived for the one or more other ones of the plurality ofluminaires 120. The first reprogramming procedure may comprise, forexample, deriving, based on the relationship strength values derived inthe adaptation portion 125-k, one or more supplementary lighting controlrules for subsequent application by the luminaire control portion 124-k.

As an example, the first reprogramming procedure may involve defining asupplementary lighting control rule that defines switching on the lightoutput of the luminaire 120-k as a response to reception of a statusindication that indicates an occurrence of the given event that pertainsto the particular other luminaire 120-p, e.g. in response to receivingthe given status indication from the particular other luminaire 120-p.Introduction of such a supplementary lighting control rule to thepreprogrammed lighting control logic at the luminaire 120-k creates anoperational dependency between luminaire 120-k and the particular otherluminaire 120-p via the luminaire 120-k following the particular otherluminaire 120-p by switching or keeping on its light output in responseto receiving the given status indication from the particular otherluminaire 120-p, which may be transmitted therefrom in response to theparticular other luminaire 120-p detecting occupancy at its location orin response to the particular other luminaire 120-p reacting tooccupancy detected at its location via activating its light output.Hence, application of the first reprogramming procedure at the luminaire120-k may be considered as self-learning at the luminaire 120-k due torelying on information collected from its operating environment in thecourse of its operation and due to being carried out without aninvolvement of an external control entity.

The first reprogramming procedure may involve the adaptation portion125-k selectively deriving a respective supplementary lighting controlrule pertaining to one or more other ones of the plurality of luminaires120 in dependence of the relationship strength values derived therefor.As an example in this regard, the adaption portion 125-k may derive thesupplementary lighting control rule for the particular other luminaire120-p in response to relationship strength value derived thereforexceeding a threshold value. Assuming an example where the relationshipstrength values are normalized into the range from 0 to 1, the thresholdvalue may comprise a fixed predefined value selected e.g. from a rangefrom 0.5 to 0.8.

As an example, the learning procedure (possibly followed by thereprogramming procedure) may be initiated in response to a user commandreceived e.g. via a user interface of the luminaire 120-k or in responseto a specific control message received at the luminaire 120-k via thecommunication portion 123-k. In the latter scenario, the control messagemay be transmitted (e.g. broadcast), e.g. from the lighting systemgateway 140 under control of the lighting system server 150, to theplurality of luminaries 120 in order to initiate the learning procedurethroughout the lighting system 100. In another example, the learningprocedure may be automatically initiated after a predefined time periodsince installing, configuring or reconfiguring the luminaire 120-k aspart of the lighting system 100. The learning procedure may be repeated,for example in response to the user command or in response to a controlmessage received via the communication portion 123-k. In anotherexample, additionally or alternatively, the learning procedure may beautomatically repeated according to a predefined schedule, e.g. atpredefined time intervals, or the learning procedure may be carried outsubstantially continuously e.g. via usage of a sliding window to definethe analysis period.

In a further example, the learning procedure may be repeated accordingto a predefined schedule with usage of an analysis period having aduration that increases from an initial duration from one learningprocedure to another until reaching a predefined maximum duration, e.g.such that the time interval between consecutive learning procedures isgradually increased and/or that the applied analysis period is graduallyincreased. As an example in this regard, the initial learning proceduremay apply a very short analysis period (e.g. a few minutes) while thelearning procedure may be first repeated at relatively short timeintervals (e.g. once in a few hours or daily) with gradually increasinganalysis period duration when more history data becomes available,whereas subsequent repetitions of the learning procedure may be carriedout at longer time intervals (e.g. once a week or once a month) usinganalysis period of the predefined maximum duration.

Referring back to the supplementary lighting control rule pertaining tothe particular other luminaire 120-p that may be defined via the firstreprogramming procedure for the lighting control logic applied by theluminaire control portion 124-k, in an example, the lighting controlaction of the supplementary lighting control rule may involve switchingon the light output of the luminaire 120-k at the predefined targetlight intensity, whereas the luminaire 120-k may report taking thislighting control action to other elements of the lighting controlnetwork via using a dedicated status indication, e.g. a fifth actionindication that indicates switching on the light output of the luminaire120-k due to the luminaire 120-k following the particular otherluminaire 120-p. The fifth action indication may further includeinformation that defines the particular other luminaire 120-p whoseactivation has triggered switching on the light output of the luminaire120-k and possibly also the relationship strength value derived for theparticular other luminaire 120-p as part of the learning procedure atthe luminaire 120-k.

Application of the fifth action indication to report application of thesupplementary lighting control rule in the particular other luminaire120-p enables the luminaire 120-k to distinguish between the particularother luminaire 120-p switching on its light output due to detectingoccupancy at its location and the particular other luminaire 120-pswitching on its light output due to following activation of a furtherluminaire, which may occur due to the learning procedure and the firstreprogramming procedure having been carried out in the particular otherluminaire 120-p. Hence, usage of the fifth action indication (instead ofthe first action indication) has e.g. the following advantages:

-   -   the luminaire control portion 124-k is able to correctly apply        the supplementary lighting control rule to switch on its light        output in response to the particular other luminaire 120-p        switching on its light output due to detecting occupancy at its        location instead of the luminaire control portion 124-k (also)        activating the light output in response to the particular other        luminaire 120-p switching its light output due to following        activation of the further luminaire;    -   a subsequent learning procedure via operation of the adaptation        portion 125-k is able to distinguish between any of the other        ones of the plurality of luminaires 120 switching on its light        output due to detecting occupancy at its location and the        respective other luminaire switching on its light output due to        following activation of the further luminaire.

In another example of configuring the supplementary lighting controlrule pertaining to the particular other luminaire 120-p, the lightingcontrol action of the supplementary lighting control rule may involveswitching on the light output of the luminaire 120-k in a mannerdifferent from that arising from operation of the first lighting controlrule described above while making use of the first action indication toreport application of this lighting control action to other elements ofthe lighting control network. Non-limiting examples in this regardinclude the following:

-   -   the lighting control action of the supplementary lighting        control rule may involve switching on the light output of the        luminaire 120-k to a secondary target light intensity that is        different from (e.g. lower than) the predefined target light        intensity applied when switching on the light output via        operation of the first lighting control rule;    -   the lighting control action of the supplementary lighting        control rule may involve switching on the light output of the        luminaire 120-k to the predefined target light intensity or to        another (e.g. lower) light intensity via a ramp-up curve        different from that applied when switching on the light output        via operation of the first lighting control rule.

In an example, the secondary target light intensity may be set to avalue that is a predefined percentage (e.g. in a range from 50% to 80%)of the predefined target light intensity, whereas in another example thesecondary target light intensity may comprise a value that isproportional to the relationship strength value derived for theparticular other luminaire 120-p. As an example of the latter, assumingthat the relationship strength values are normalized into the range from0 to 1, the secondary target light intensity may be derived viamultiplying the predefined target light intensity by the relationshipstrength value derived for the particular other luminaire 120-p. In anexample, the ramp-up curve applied in switching on the light output ofthe luminaire 120-k via operation of the supplementary lighting controlrule may define increasing the light intensity to the applicable targetlight intensity slower (e.g. over a longer time period) than whenswitching on the light output via operation of the first lightingcontrol rule.

Hence, in this example the luminaire 120-k is able to distinguishbetween the particular other luminaire 120-p switching on its lightoutput due to detecting occupancy at its location and the particularother luminaire 120-p switching on its light output due to followingactivation of a further luminaire via further observing the change inlight level at the location of the luminaire 120-k (e.g. based on thelocal light level indications available in the luminaire 120-k) uponreceiving the given status indication. This is applicable both forcarrying out a subsequent learning procedure in the luminaire 120-k andin application of the supplementary lighting control rule in theluminaire 120-k.

In the course of the learning procedure the adaptation portion 125-k mayfurther derive a respective distance measure for the one or more otherones of the plurality of luminaires 120. A distance measure thatpertains to the particular other luminaire 120-p may be descriptive of adistance between the luminaire 120-k and the particular other luminaire120-p and it may be computed based on respective distance values derivedfor one or more messages received at the luminaire 120-k from theparticular other luminaire 120-p, e.g. as a statistical measure such asa minimum, an average, a median or a maximum of distance values underconsideration. An example of an applicable distance measure comprises areceived signal strength indication (RSSI) measure computed based onrespective RSSI values derived for individual status messages receivedfrom the particular other luminaire 120-p. In this regard, a RSSImeasure having a high(er) value typically implies a short(er) distancebetween the luminaire 120-k and the particular other luminaire 120-pwhile a RSSI measure having a low(er) value typically implies a long(er)distance between the luminaire 120-k and the particular other luminaire120-p, the RSSI measure thereby serving as an indication of the distancebetween these two elements of the lighting control network e.g. inscenarios where the luminaire 120-k receives the status messagesdirectly from the particular other luminaire 120-p (i.e. without thestatus messages being relayed by intermediate nodes of the lightingcontrol network).

Another example of an applicable distance measure comprises a hop countmeasure computed based on hop counts observed for individual statusmessages originating from the particular other luminaire 120-p (e.g.received in header parts of respective status messages originating fromthe particular other luminaire 120-p). In this regard, a low hop countmeasure indicates a short(er) distance between the luminaire 120-k andthe particular other luminaire 120-p while a high hop count measureindicates a long(er) distance between the luminaire 120-k and theparticular other luminaire 120-p, and, consequently, the hop countmeasure may serve as indication of the distance between the luminaire120-k and the particular other luminaire 120-p e.g. in scenarios wherethe status messages originating from the particular other luminaire120-p are relayed to the luminaire 120-k via one or more intermediatenodes of the lighting control network (e.g. via a mesh network).

The adaptation portion 125-k may operate the communication portion 123-kto transmit the distance measures derived by the adaptation portion125-k via the lighting system gateway 140 to the lighting system server150. This information may be transmitted from the luminaire 120-k to thelighting system server 150 as part of the relationship data described inthe foregoing. Hence, the relationship data may further include therespective distance measure derived for the one or more other ones ofthe plurality of luminaires 120 together with the luminaire IDs of therespective luminaries.

FIG. 3 illustrates a block diagram of some (logical) components of thelighting system gateway 140 according to an example, comprising acommunication portion 143 and a control portion 144. The communicationportion 143 may be provided for wireless communication with otherelements of the lighting control network (e.g. the plurality ofluminaires 120) and for wireless or wired communication with thelighting system server 150. The control portion 144 may be provided forcontrolling at least some aspects of operation of the lighting systemgateway 140 in terms of facilitating lighting control within thelighting system 100. In an example, the lighting system gateway 140 maycomprise an apparatus comprising a processor and a memory, where thememory is arranged to store computer program code that, when executed bythe processor, causes the apparatus to operate as the control portion144 of the lighting system gateway 140 according to the presentdisclosure. More detailed examples of using the processor and the memoryfor implementing the luminaire lighting system gateway 140 are describedlater in this text with references to FIG. 6 .

According to an example, the control portion 144 of the lighting systemgateway 140 may receive, via the communication portion 143, therespective relationship data from the plurality of luminaires and relay,via the communication portion 143, the received relationship data to thelighting system server 150 for processing therein. Moreover, the controlportion 144 may receive, via the communication portion 143, dependencycontrol information from the lighting system server 150 and relay, viathe communication portion 153, the dependency control information to theplurality of luminaires 120.

FIG. 4 illustrates a block diagram of some (logical) components of thelighting system server 150 according to an example, comprising acommunication portion 153 for wireless or wired communication with otherapparatuses, e.g. with the lighting system server 140, and a controlportion 154 for processing the respective relationship data received viathe lighting system gateway 140 from the plurality of luminaires 120. Inthis regard, the control portion 154 may receive, via the communicationportion 153, respective relationship data originating from the pluralityof luminaires 120, control at least one aspect of operationaldependencies among the plurality of luminaires 120 in accordance withthe relationship data received therein, and transmit, via thecommunication portion 153, dependency control information derivedtherein via the lighting system gateway 140 to the plurality ofluminaires 120.

In an example, the lighting system server 150 may comprise a logicalentity implemented by one or more apparatuses that each comprise aprocessor and a memory, where the memory at each of the one or moreapparatuses is arranged to store a respective computer program codethat, when executed by the processor of the respective apparatus, causesthe one or more apparatuses to jointly operate as the control portion154 of the lighting system server 150 according to the presentdisclosure. More detailed examples of using the processor and the memoryfor implementing such an apparatus are described later in this text withreferences to FIG. 6 .

In an example, some aspects of operation of the lighting system 100 maybe configured based on the respective relationship data derived at theplurality of luminaires 120 via operation of the control portion 154 ofthe lighting system server 150. Such lighting system configuration maybe carried out, for example, via implementing a method 200 illustratedin FIG. 5 , where the method 200 may comprise the following stepscarried out in at least some luminaires of the plurality of luminaires120:

-   -   controlling the light output of a respective luminaire 120-k in        accordance with the preprogrammed lighting control logic that        defines switching on the light output of the respective        luminaire 120-k in response to detecting occupancy at location        of the respective luminaire 120-k (block 202);    -   transmitting status indications to other ones of the plurality        of luminaires 120 and receiving status indications from other        ones of the plurality of luminaires 120, wherein each status        indication is descriptive of an occurrence of an event        pertaining to a luminaire transmitting the respective status        indication (blocks 204 a and 204 b);    -   deriving the relationship data including one or more        relationship strength values, wherein each relationship strength        value pertains to a particular other luminaire 120-p of the        plurality of luminaires 120 and is descriptive of an extent of        regularity at which reception of a status indication that        indicates an occurrence of a given event that pertains to the        particular other luminaire 120-p is followed by detection of        occupancy at the location of the respective luminaire 120-k;        (block 206); and    -   transmitting the relationship data to the lighting system server        150; (block 208),

Moreover, the method 200 may further comprise controlling, in thelighting system server 150, at least one aspect of operationaldependencies among the plurality of luminaires 120 in accordance withthe respective relationship data received from the plurality ofluminaires 120 (block 210).

The respective operations described with references to the method stepsrepresented by blocks 202 to 210 may be varied or complemented in anumber of ways, e.g. according to the examples described in theforegoing and/or in the following in context of describing respectivecharacteristics of operation of the plurality of luminaires 120(predominantly via references to the luminaire 120-k) and/or thelighting system server 150. Moreover, the method 200 may be complementedwith one or more additional steps, the order of carrying out at leastsome of the method steps may be different from that depicted in FIG.and/or some of the steps may be omitted without departing from the scopeof the lighting system configuration procedure described in the presentdisclosure.

Referring now to operations that pertain to block 210, the aspect of thecontrol portion 154 of the lighting system server 150 controllingoperational dependencies among the plurality of luminaires 120 mayinvolve the control portion 154 carrying out, for example, one of thefollowing:

-   -   determining a respective luminaire group for at least one of the        plurality of luminaires 120 based on the relationship data        received from the plurality of luminaires 120,    -   preventing, based on the relationship data received from the        plurality of luminaires 120, an operational dependency between        one or more pairs of luminaires among the plurality of        luminaires 120,    -   creating, based on the relationship data received from the        plurality of luminaires 120, respective one or more further        operational dependencies for at least one of the plurality of        luminaires 120.

In a first scenario, operations that pertain to block 210 may comprisethe control portion 154 in the lighting system server 150 determining arespective luminaire group for at least one luminaire of the pluralityof luminaires 120 based on the respective relationship strength valuesreceived from the plurality of luminaires 120 in the respectiverelationship data, thereby determining the one or more luminaire groupsfor the lighting system 100. In general, two luminaires that havereported a relatively high relationship strength values pertaining toeach other may be assigned to the same luminaire group. As an example,this may involve the control portion 154 determining the luminaire groupfor the luminaire 120-k based on respective relationship strength valuesreported for one or more other luminaires of the lighting system 100 bythe respective luminaire 120-k and on respective relationship strengthvalues reported for the respective luminaire 120-k by said one or moreother luminaires.

In an example in this regard, the control portion 154 may assign thoseluminaires that have reported for the luminaire 120-k a relationshipstrength value that exceeds a grouping threshold and for which theluminaire 120-k has reported a relationship strength value that exceedsthe grouping threshold into a luminaire group of the luminaire 120-k.Assuming an example where the relationship strength values arenormalized into the range from 0 to 1, the grouping threshold may be afixed predefined value selected e.g. from a range from 0.5 to 0.8. Suchan approach may result in determining for the luminaire 120-k aluminaire group including one or more other luminaires that are all arein relatively close proximity of the luminaire 120-k. In anotherexample, the control portion 154 may apply a clustering algorithm knownin the art, such as minimum-cut method, hierarchical clustering orGirvan-Newman algorithm, for identifying possible community structuresamong the plurality of luminaire and, consequently, for determining theluminaire group for the luminaire 120-k.

Such an approach may allow for determining for the luminaire 120-k aluminaire group that includes luminaire that are (also) further awayfrom the luminaire 120-k but that still exhibit a significantoperational relationship with the luminaire 120-k,

The resulting luminaire groups are symmetric in that if the luminaire120-k has the particular other luminaire 120-p assigned to its luminairegroup, the particular other luminaire 120-p has the luminaire 120-kassigned to its luminaire group. Depending on the relationship strengthvalues determined by the luminaire 120-k to one or more other ones ofthe plurality of luminaries 120 and the respective relationshipstrengths determined for the luminaire 120-k by the one or more otherones of the plurality of luminaries 120, the luminaire 120-k may beassigned into respective luminaire groups of more than one otherluminaires and it may have one or more other luminaires assigned to itsluminaire group, whereas the luminaire 120-k does not necessarily belongto a respective luminaire group any of the other luminaires and/or theluminaire 120-k does not necessarily have a luminaire group determinedtherefor.

Still referring to the first scenario, operations that pertain to block210 may comprise the control portion 154 operating the communicationportion 153 to transmit, via the lighting system gateway 140 to theplurality of luminaires 120, dependency control information thatincludes information that defines the luminaire groups determined at thelighting system server 150. Hence, each luminaire of the lighting system100 for which a respective luminaire group has been determined viaoperation of the control portion 154 of the lighting system server 150receives information of the respective luminaire group determinedtherefor. Consequently, in response to receiving the information of theluminaire group determined therefor, the adaptation portion 125-k in theluminaire 120 may carry out a second reprogramming procedure that mayinvolve deriving one or more further lighting control rules forsubsequent application by the luminaire control portion 124-k.

As an example, the second reprogramming procedure may involve definingone or more further lighting control rules that define switching on thelight output of the luminaire 120-k as a response to reception of astatus indication that indicates an occurrence of the given event thatpertains to any of the other luminaires assigned to the luminaire groupdetermined for the luminaire 120-k, e.g. in response to receiving astatus indication that at least indirectly indicates a change fromnon-occupancy to occupancy observed at any of the other luminairesassigned to the luminaire group determined for the luminaire 120-k. Inthis regard, the status indication under consideration may comprise e.g.one of the following:

-   -   an action indication that indicates switching on the light        output received from any other luminaire assigned to the        luminaire group determined for the luminaire 120-k, e.g. the        first action indication described in the foregoing,    -   an occupancy sensor data indication that indicates a change of        occupancy state from non-occupancy to occupancy received from        any other luminaire assigned to the luminaire group determined        for the luminaire 120-k.

Introduction of such one or more further lighting control rules to thepreprogrammed lighting control logic at the luminaire 120-k creates arespective operational dependency between luminaire 120-k and the one ormore luminaires assigned to the luminaire group determined for theluminaire 120-k via the luminaire 120-k following the other luminairesof this luminaire group by activating its light output in response toany of the other luminaires assigned to this luminaire group detectingoccupancy at its respective location and/or in response to any of theother luminaires assigned to this luminaire group reacting to occupancydetected at its respective location via activating its light output.

The respective lighting control actions applied by the one or morefurther lighting control rules may be similar to that applied by thesupplementary lighting control rule described in the foregoing, mutatismutandis. In particular, in an example, the lighting control action of afurther lighting control rule may involve switching on the light outputat the predefined target light intensity and reporting application ofthis lighting control action to other elements of the lighting controlnetwork via usage of the dedicated action indication, e.g. the fifthaction indication described above, whereas in another example, thelighting control action of a further lighting control rule may involveswitching on the light output in a manner different from that arisingfrom operation of the first lighting control rule and reportingapplication of the lighting control action of the further lightingcontrol rule to other elements of the lighting control network via usageof the first action indication or the dedicated action indication (e.g.the fifth action indication described above).

The second reprogramming procedure may further involve the adaptationportion 125-k deleting, disabling or deactivating the one or moresupplementary lighting control rules possible introduced earlier tosupplement the preprogrammed lighting logic applied by the luminairecontrol portion 124-k via operation of the first reprogrammingprocedure, thereby removing or deleting the operational dependenciespossibly created via operation of the first reprogramming procedure.

In a second scenario, operations that pertain to block 210 may comprisethe control portion 154 in the lighting system server 150 preventing anoperational dependency between one or more pairs of luminaires among theplurality of luminaires 120 based on the respective distance measuresreceived from the plurality of luminaires 120 in the respectiverelationship data. In this regard, as described in the foregoing, therelationship data received from the luminaire 120-k may comprise therespective distance measure pertaining to one or more other ones of theplurality of luminaires, whereas the control portion 154 may preventoperational dependencies between two luminaires for which the distancemeasures received in the relationship indicate a distance that exceeds adistance threshold. Preventing an operational dependency between acertain pair of luminaires may comprise cancelling or removing anexisting operational dependency defined for the certain pair ofluminaires or preventing creation of an operational dependency for thecertain pair of luminaires. Such prevention of operational dependencymay enable avoiding a first luminaire creating or maintaining anoperational dependency on a second luminaire e.g. in scenarios where thesecond luminaire is located at a substantial distance from the firstluminaire, where the second luminaire is located in a different floor ofa building than the first luminaire and/or where a wall or acorresponding structure separates the second luminaire from the firstluminaire. Preventing an operational dependency of the first luminaireon the second luminaire may be considered as ‘blacklisting’ of thesecond luminaire for the first luminaire.

As an example in this regard, the control portion 154 may prevent anoperational dependency of the luminaire 120-k on the particular otherluminaire 120-p in case the distance measure pertaining to theparticular other luminaire 120-p reported by the luminaire 120-ksuggests a distance that exceeds the distance threshold and/or in casethe in case the distance measure pertaining to luminaire 120-k reportedby the particular other luminaire 120-p suggests a distance that exceedsthe distance threshold. Prevention of the operational dependency mayinvolve cancellation or removal of an operational dependency defined inthe luminaire 120-k as a consequence of the first reprogrammingprocedure applied therein (e.g. via removal of one or more supplementarylighting control rules derived via self-learning at the luminaire 120-k)or cancellation or removal of an operational dependency defined in theluminaire 120-k as a consequence of the second reprogramming procedureapplied therein (e.g. via removal of one or more further lightingcontrol rules derived in the luminaire 120-k for implementing theluminaire group determined therefor by the lighting system server 150).Moreover, prevention of the operational dependency may involve excludinga certain luminaire from consideration in derivation of the luminairegroup for the luminaire 120-k by the control portion 154 of the lightingsystem server 150.

In case RSSI-based distance estimation is applied at the plurality ofluminaires 120, the distance threshold may comprise a RSSI thresholdvalue and the control portion 154 may prevent the operational dependencyof the luminaire 120-k on the particular other luminaire 120-p inresponse to one of following:

-   -   the RSSI measure pertaining to the particular other luminaire        120-p reported by the luminaire 120-k failing to exceed the RSSI        threshold value,    -   the RSSI measure pertaining to the luminaire 120-k reported by        the particular other luminaire 120-p failing to exceed the RSSI        threshold value,    -   any of the RSSI measure pertaining to the particular other        luminaire 120-p reported by the luminaire 120-k or the RSSI        measure pertaining to the luminaire 120-k reported by the        particular other luminaire 120-p failing to exceed the RSSI        threshold value,    -   both the RSSI measure pertaining to the particular other        luminaire 120-p reported by the luminaire 120-k and the RSSI        measure pertaining to the luminaire 120-k reported by the        particular other luminaire 120-p failing to exceed the RSSI        threshold value.

In an example, the RSSI threshold value may comprise a fixed predefinedvalue, whereas in another example the RSSI threshold value may comprisea value derived based RSSI measures reported by the luminaire 120-kand/or reported for the luminaire 120-k by other ones of the pluralityof luminaires 120. As an example of the latter, the RSSI threshold valuemay be derived as predefined percentage of the highest RSSI measurereported by the luminaire 120-k for any of the other ones of theplurality of luminaires 120 and/or reported for the luminaire 120-k byany of the other ones of the plurality of luminaires 120.

In case hop-count-based distance estimation is applied at the pluralityof luminaires 120, the distance threshold may comprise a hop countthreshold and the control portion 154 may prevent the operationaldependency of the luminaire 120-k on the particular other luminaire120-p in response to one of following:

-   -   the hop count measure pertaining to the particular other        luminaire 120-p reported by the luminaire 120-k exceeding the        hop count threshold,    -   the hop count measure pertaining to the luminaire 120-k reported        by the particular other luminaire 120-p exceeding the hop count        threshold,    -   any of the hop count measure pertaining to the particular other        luminaire 120-p reported by the luminaire 120-k or the hop count        measure pertaining to the luminaire 120-k reported by the        particular other luminaire 120-p exceeding the hop count        threshold,    -   both the hop count measure pertaining to the particular other        luminaire 120-p reported by the luminaire 120-k and the hop        count measure pertaining to the luminaire 120-k reported by the        particular other luminaire 120-p exceeding the hop count        threshold.

In an example, the hop count threshold may comprise a fixed predefinedthreshold, whereas in another example the hop count threshold maycomprise a value derived based hop count measures reported by theluminaire 120-k and/or reported for the luminaire 120-k by other ones ofthe plurality of luminaires 120. As an example of the latter, the hopcount threshold may be derived as predefined percentage of the highesthop count measure reported by the luminaire 120-k for any of the otherones of the plurality of luminaires 120 and/or reported for theluminaire 120-k by any of the other ones of the plurality of luminaires120.

Still referring to the second scenario, operations that pertain to block210 may comprise the control portion 154 operating the communicationportion 153 to transmit, via the lighting control gateway 140 to theplurality of luminaires 120, dependency control information that definesone or more operational dependencies to be prevented at one or more ofthe plurality of luminaires 120. Hence, each luminaire of the lightingsystem 100 that is to prevent one or more operational dependencies on acertain other luminaire may receive the information in this regard andtake necessary action therein. Consequently, in an example, in responseto receiving the information of the one or more operational dependenciesto be prevented therein, the adaptation portion 125-k in the luminaire120-k may carry out a third reprogramming procedure that may involvedeleting, disabling or inactivating any supplementary lighting controlrules and/or further lighting control rules possibly defined thereinaccordingly for subsequent operation of the luminaire control portion124-k.

In a third scenario, operations that pertain to block 210 may comprisethe control portion 154 in the lighting system server 150 creating orintroducing one or more respective further operational dependencies forone or more luminaires of the lighting system 100, wherein creation orintroduction of the one or more further operational dependencies may bebased on the respective relationship strength values received from theplurality of luminaires 120 in the respective relationship data.

As an example in this regard, the control portion 154 may identify asituation where the luminaire 120-k has reported a relatively highrelationship strength value for the particular other luminaire 120-pwhile the particular other luminaire 120-p has reported a relatively lowrelationship value for the luminaire 120-k and create, for the luminaire120-k an operational dependency on the particular other luminaire 120-p.Such an operation accounts e.g. for a scenario where the particularother luminaire 120-p is located in a first space (e.g. in a room)accessible via a second space (e.g. a corridor, a lobby, a staircase,etc.) and the luminaire 120-k is located in the second space relativelyclose to an entrance to the first space. Consequently, it may beadvantageous to keep the second space illuminated (at least to someextent) when the first space is occupied to ensure illumination in thesecond space when a person exits from the first space to the secondspace.

In an example, the control portion 154 may implement the above-describedoperation via creating the further operational dependency for theluminaire 120-k in response to

-   -   the relationship strength value for the particular other        luminaire 120-p reported by the luminaire 120-k exceeding a        first threshold, and    -   the relationship strength value for the luminaire 120-k reported        by the particular other luminaire 120-p failing to exceed a        second threshold that is lower than the first threshold.

Herein, the first threshold may be the same as or the similar to thegrouping threshold described in the foregoing, whereas the secondthreshold may have a substantially lower value. Assuming an examplewhere the relationship strength values are normalized into the rangefrom 0 to 1, the second threshold may be a fixed predefined valueselected e.g. from a range from 0.1 to 0.2.

Still referring to the third scenario, operations that pertain to block210 may comprise the control portion 154 operating the communicationportion 153 to transmit, via the lighting system gateway 140 to theplurality of luminaires 120, dependency control information that definesone or more further operational dependencies to be introduced at one ormore of the plurality of luminaires 120. Hence, each luminaire of thelighting system 100 that is to introduce one or more further operationaldependencies determined therefor may receive information of theoperational dependencies to be introduced. Consequently, in response toreceiving the information of the one or more operational dependencies tobe introduced therein, the adaptation portion 125-k in the luminaire120-k may carry out a fourth reprogramming procedure that may involveintroducing one or more additional lighting control rules for subsequentoperation of the luminaire control portion 124-k. In this regard, anadditional lighting control rule pertaining to the particular otherluminaire 120-p may define switching on and/or keeping on the lightoutput of the luminaire 120-k as a response to reception of a statusindication that indicates an occurrence of a given event that pertainsto the particular other luminaire 120-p, e.g. in response to receiving astatus indication that at least indirectly indicates detecting occupancyat the location of the particular other luminaire 120-p. As an examplein this regard, the additional lighting control rule pertaining to theparticular other luminaire 120-p may define switching on and/or keepingon the light output of the luminaire 120-k as a response to receivingone of the following from the particular other luminaire 120-p:

-   -   an action indication that indicates switching on the light        output of the particular other luminaire 120-p, e.g. the first        action indication described in the foregoing,    -   an action indication that indicates keeping on the light output        of the particular other luminaire 120-p, e.g. the third action        indication described in the foregoing,    -   an occupancy sensor data indication that indicates occupancy        detected at the particular other luminaire 120-p.

In another example, additionally or alternatively, an additionallighting control rule pertaining to the particular other luminaire 120-pintroduced via the fourth reprogramming procedure may define switchingon and/or keeping on the light output of the luminaire 120-k as aresponse to reception of a status indication that indicates anoccurrence of a second given event that pertains to the particular otherluminaire 120-p, e.g. in response to detecting a change in occupancystate from occupancy to non-occupancy at the location of the particularother luminaire 120-p. As an example in this regard, the additionallighting control rule pertaining to the particular other luminaire 120-pmay define switching on and/or keeping on the light output of theluminaire 120-k as a response to receiving one of the following from theparticular other luminaire 120-p:

-   -   an action indication that indicates initiating adjustment of the        light output of the particular other luminaire 120-p to the        stand-by light intensity, e.g. the second action indication        described in the foregoing,    -   an occupancy sensor data indication that indicates a change of        occupancy state from occupancy to non-occupancy detected at the        particular other luminaire 120-p.

In an example, introduction of the additional lighting control rulepertaining to the particular other luminaire 120-p for the luminaire120-k via the fourth reprogramming procedure may be dependent on thelight output of the particular other luminaire 120-p being visible to(the location of) the luminaire 120-k and/or the light output of theluminaire 120-k being visible to (the location of) the particular otherluminaire 120-p. As an example in this regard, the luminaire controlportion 124-k in the luminaire 120-k may detect the particular otherluminaire 120-p being visible thereto in response to the local lightlevel indications derived at the luminaire 120-k (and recorded in thehistory data therein) indicating an increase in light level that exceedsa predefined threshold upon the particular other luminaire 120-pswitching on its light output. In another example, the particular otherluminaire 120-p may detect visibility of the luminaire 120-k therein ina similar manner and report the visibility or non-visibility of theluminaire 120-k therein e.g. via a transmitting a message to theluminaire 120-k via the lighting control network.

In the foregoing, the aspect of controlling at least one aspect ofoperational dependencies among the plurality of luminaires 120 (cf.block 210 of the method 200) is described as an operation carried outvia operation of the control portion 154 of the lighting system server150. This is, however, a non-limiting example and in other examples suchcontrol of operational dependences among the plurality of luminaires 120may be implemented via operation of the lighting control gateway 140 orjointly via respective operation of the lighting control gateway 140 andthe lighting system server 150. Consequently, the aspect of controllingat least one aspect of operational dependencies among the plurality ofluminaires 120 may be carried out by a lighting system control entity,which may comprise the lighting system gateway 140 and/or the systemserver 150.

The lighting system configuration described in the foregoing via anumber of examples provides automated control over at least some aspectsof operational dependencies among the plurality of luminaires 120 of thelighting system 100 by controlling the operational dependencies viaoperating the luminaires 120-k of the lighting system 100 in theiractual operating environment, which ensures basing the operationaldependencies among the plurality of luminaires 120 on (relationship)data obtained in actual operating conditions of the lighting system 100.Hence, the disclosed approach does not only enable avoiding tediousmanual configuration of the operational dependencies among the pluralityof luminaires 120 but also facilitates controlling the operationaldependencies in a manner that ensures user comfort due to sufficientlighting in locations of the illuminated space where one or moreoccupants are detected and/or where one or more occupants are expectedto move.

While the lighting system configuration procedure is described in theforegoing as a stand-alone procedure, the automated procedure viaoperation of the method 200 may be, alternatively, complemented bymanual configuration of operational dependencies between some of theplurality of luminaires 120.

FIG. 6 illustrates a block diagram of some components of an apparatus300 that may be employed to implement at least some of the operationsdescribed with references to the luminaire control apparatus 126-k, withreferences to the control portion 144 or with reference to the controlportion 154. The apparatus 300 comprises a processor 310 and a memory320. The memory 320 may store data and computer program code 325. Theapparatus 300 may further comprise communication means 330 for wired orwireless communication with other apparatuses, where the communicationmeans 330 may comprise respective one of the communication portion123-k, the communication portion 143 or the communication portion 153.The apparatus 300 may further comprise user I/O (input/output)components 340 that may be arranged, together with the processor 310 anda portion of the computer program code 325, to provide a user interfacefor receiving input from a user and/or providing output to the user. Inparticular, the user I/O components may include user input means, suchas one or more keys or buttons, a keyboard, a touchscreen or a touchpad,etc. The user I/O components may include output means, such as a displayor a touchscreen. The components of the apparatus 300 arecommunicatively coupled to each other via a bus 350 that enablestransfer of data and control information between the components.

The memory 320 and a portion of the computer program code 325 storedtherein may be further arranged, with the processor 310, to cause theapparatus 300 to perform at least some aspects of operation of therespective one of the luminaire control apparatus 126-k, the controlportion 144 or the control portion 154. The processor 310 is configuredto read from and write to the memory 320. Although the processor 310 isdepicted as a respective single component, it may be implemented asrespective one or more separate processing components. Similarly,although the memory 320 is depicted as a respective single component, itmay be implemented as respective one or more separate components, someor all of which may be integrated/removable and/or may providepermanent/semi-permanent/dynamic/cached storage.

The computer program code 325 may comprise computer-executableinstructions that implement at least some aspects of operation of therespective one of the luminaire control apparatus 126-k, the controlportion 144 or the control portion 154 when loaded into the processor310. As an example, the

computer program code 325 may include a computer program consisting ofone or more sequences of one or more instructions. The processor 310 isable to load and execute the computer program by reading the one or moresequences of one or more instructions included therein from the memory320. The one or more sequences of one or more instructions may beconfigured to, when executed by the processor 310, cause the apparatus300 to perform at least some aspects of operation of respective one ofthe luminaire control apparatus 126-k, the control portion 144 or thecontrol portion 154. Hence, the apparatus 300 may comprise at least oneprocessor 310 and at least one memory 320 including the computer programcode 325 for one or more programs, the at least one memory 320 and thecomputer program code 325 configured to, with the at least one processor310, cause the apparatus 300 to perform at least some aspects ofoperation of the respective one of the luminaire control apparatus126-k, the control portion 144 or the control portion 154.

The computer program code 325 may be provided e.g. a computer programproduct comprising at least one computer-readable non-transitory mediumhaving the computer program code 325 stored thereon, which computerprogram code 325, when executed by the processor 310 causes theapparatus 300 to perform at least some aspects of operation of therespective one of the luminaire control apparatus 126-k, the controlportion 144 or the control portion 154. The computer-readablenon-transitory medium may comprise a memory device or a record mediumthat tangibly embodies the computer program. As another example, thecomputer program may be provided as a signal configured to reliablytransfer the computer program.

Reference(s) to a processor herein should not be understood to encompassonly programmable processors, but also dedicated circuits such asfield-programmable gate arrays (FPGA), application specific circuits(ASIC), signal processors, etc.

1. A method in a lighting system comprising a lighting system controlentity and a plurality of luminaires that are wirelessly coupled to thelighting system control entity, wherein the method comprises, in aluminaire of the plurality of luminaires: controlling a light output ofthe respective luminaire in accordance with a preprogrammed lightingcontrol logic that defines switching on the light output in response todetecting occupancy at the respective luminaire, transmitting statusindications to and receiving status indications from other ones of theplurality of luminaires, wherein each status indication is descriptiveof an occurrence of an event pertaining to a luminaire transmitting therespective status indication, deriving relationship data including oneor more relationship strength values, wherein each relationship strengthvalue pertains to a particular other luminaire of said plurality ofluminaires and is descriptive of an extent of regularity at whichreception of a status indication that indicates an occurrence of a givenevent pertaining to the particular other luminaire is followed withdetecting occupancy at the respective luminaire, and transmitting therelationship data to the lighting system control entity; and wherein themethod comprises, in the lighting system control entity, controlling atleast one aspect of operational dependencies among the plurality ofluminaires in accordance with the relationship data received from theplurality of luminaires.
 2. A method according to claim 1, wherein saidgiven event is at least indirectly indicative of a change of occupancystate at the particular other luminaire from non-occupancy to occupancyand wherein deriving the relationship strength value comprisesdetermining the extent of regularity at which reception of a givenstatus indication from the particular other luminaire is followed with achange in occupancy state from non-occupancy to occupancy at therespective luminaire, wherein the given status indication includes oneof the following: an indication of the particular other luminaireswitching on its light output, or an indication of a change in occupancystate from non-occupancy to occupancy at the particular other luminaire.3. A method according to claim 1, wherein controlling at least oneaspect of operational dependency among the plurality of luminairescomprises determining a respective luminaire group for at least oneluminaire of the plurality of luminaires based on the relationship datareceived from the plurality of luminaires, wherein the luminaire groupdetermined for the respective luminaire includes one or more otherluminaires of the plurality of luminaires.
 4. A method according toclaim 3, wherein the method further comprises, in each of said at leastone luminaire, introducing one or more further lighting control rules tothe preprogrammed lighting control logic in the respective luminaire,wherein said one or more further lighting control rules define switchingon the light output of the respective luminaire as a response toreception of a status indication that indicates an occurrence of thegiven event pertaining to any of the one or more other luminairesincluded in the luminaire group determined for the respective luminaire.5. A method according to claim 3, wherein determining the luminairegroup for the respective luminaire comprises assigning one or more otherluminaires to a luminaire group of the respective luminaire based onrespective relationship strength values reported for said one or moreother luminaires with the respective luminaire and on respectiverelationship strength values reported for the respective luminaire withsaid one or more other luminaires.
 6. A method according to claim 1,wherein the method further comprises, in each of the plurality ofluminaires, deriving a respective distance measure for one or more otherluminaires based on status messages carrying status indications receivedtherefrom, wherein each distance measure is descriptive of a distancebetween the respective luminaire and a respective one of said one ormore other luminaires, and transmitting the distance measures to thelighting system control entity, and wherein controlling at least oneaspect of operational dependency among the plurality of luminairescomprises preventing an operational dependency between one or more pairsof luminaires based on the distance measures received from the pluralityof luminaires.
 7. A method according to claim 6, wherein the distancemeasure derived in the respective luminaire for the particular otherluminaire comprises a received signal strength indication measure thatis computed based on respective received signal strength indicationvalues derived for one or more status messages received from theparticular other luminaire.
 8. A method according to claim 6, whereinpreventing the operational dependency comprises preventing theoperational dependency between a respective luminaire and a particularanother luminaire as a response to the distance measure reported for theparticular other luminaire with the respective luminaire indicating adistance that exceeds at least one of a distance threshold and/or or thedistance measure reported for the respective luminaire with theparticular other luminaire indicating a distance that exceeds thedistance threshold.
 9. A method according to claim 6, wherein preventingthe operational dependency between the respective luminaire and theparticular other luminaire comprises one of the following: preventingcreation of the operational dependency between the respective luminaireand the particular other luminaire, or cancelling an operationaldependency created between the respective luminaire and the particularother luminaire.
 10. A method according to claim 9, wherein cancellingthe operational dependency created between the respective luminaire andthe particular other luminaire comprises one or both of the following:deleting, in the respective luminaire, a lighting control rule thatdepends on reception of a status indication that indicates an occurrenceof the given event pertaining to the particular other luminaire, ordeleting, in the particular other luminaire, a lighting control rulethat depends on reception of a status indication that indicates anoccurrence of the given event pertaining to the respective luminaire.11. A method according to claim 1, wherein controlling at least oneaspect of operational dependency among the plurality of luminairescomprises creating an operational dependency between the respectiveluminaire and the particular other luminaire in dependence of therespective relationship strength values received therefrom; and whereinthe method further comprises, in the respective luminaire, introducingan additional lighting control rule to the preprogrammed lightingcontrol logic therein, wherein the additional lighting control ruledefines switching on the light output of the respective luminaire as aresponse to reception of a status indication that indicates anoccurrence of the given event pertaining to the particular otherluminaire.
 12. A method according to claim 11, wherein creating theoperational dependency between the respective luminaire and theparticular other luminaire comprises creating the operational dependencyin response to: the relationship strength value for the particular otherluminaire reported with the respective luminaire exceeding a firstthreshold, and the relationship strength value for the respectiveluminaire reported with the particular other luminaire failing to exceeda second threshold that is smaller than the first threshold.
 13. Amethod according to claim 11, wherein additional lighting control ruledefines switching or keeping on the light output of the respectiveluminaire as a response to receiving a status indication that indicatesoccupancy at the particular other luminaire and wherein said statusindication includes one of the following: an indication of theparticular other luminaire switching or keeping on its light output, oran indication of a change in occupancy state from non-occupancy tooccupancy or an indication of continued occupancy at the location of theparticular other luminaire.
 14. A method according to claim 11, whereinadditional lighting control rule defines switching or keeping on thelight output of the respective luminaire as a response to receiving astatus indication that indicates occupancy at the particular otherluminaire and wherein said status indication includes one of thefollowing: an indication of the particular other luminaire initiatingadjustment of its light output to a stand-by light intensity, anindication of a change in occupancy state from occupancy tonon-occupancy at the location of the particular other luminaire.
 15. Alighting system comprising a lighting system control entity and aplurality of luminaires that are wirelessly coupled to the lightingsystem control entity, wherein a luminaire of the plurality ofluminaries comprises: a luminaire control portion arranged to control alight output of a respective luminaire in accordance with apreprogrammed lighting control logic that defines switching on the lightoutput in response to detecting occupancy at the respective luminaire,and transmit status indications to and receive status indications fromother ones of the plurality of luminaires, wherein each statusindication is descriptive of an occurrence of an event pertaining to aluminaire transmitting the respective status indication; and anadaptation portion arranged to derive relationship data including one ormore relationship strength values, wherein each relationship strengthvalue pertains to a particular other luminaire of said plurality ofluminaires and is descriptive of an extent of regularity at whichreception of a status indication that indicates an occurrence of a givenevent pertaining to the particular other luminaire is followed withdetecting occupancy at the respective luminaire, and transmit therelationship data to the lighting system control entity; and wherein thelighting system control entity comprises a control portion arranged tocontrol at least one aspect of operational dependencies among theplurality of luminaires in accordance with the relationship datareceived from the plurality of luminaires.
 16. A lighting systemaccording to claim 15, wherein the control portion of the lightingsystem control entity is arranged to determine a respective luminairegroup for at least one luminaire of the plurality of luminaires based onthe relationship data received from the plurality of luminaires, whereinthe luminaire group determined for the respective luminaire includes oneor more other luminaires of the plurality of luminaires.
 17. A lightingsystem according to claim 16, wherein the control portion of thelighting system control entity is arranged to assign one or more otherluminaires to a luminaire group of the respective luminaire based onrespective relationship strength values reported for said one or moreother luminaires with the respective luminaire and on respectiverelationship strength values reported for the respective luminaire withsaid one or more other luminaires.
 18. A lighting system according toclaim 15, wherein the plurality of luminaires is arranged to derive arespective distance measure for one or more other luminaires based onstatus messages carrying status indications received therefrom, whereinthe distance measure is descriptive of a distance between the respectiveluminaire and a respective one of said one or more other luminaires, andtransmit the distance measures to the lighting system control entity,and wherein the control portion of the lighting system control entity isarranged to prevent an operational dependency between one or more pairsof luminaires based on the distance measures received from the pluralityof luminaires.
 19. A lighting system according to claim 15, wherein thecontrol portion of the lighting system control entity is arranged tocreate an operational dependency between the respective luminaire andthe particular other luminaire in dependence of the respectiverelationship strength values received therefrom; and wherein theplurality of luminaires is arranged to introduce an additional lightingcontrol rule to the preprogrammed lighting control logic therein,wherein the additional lighting control rule defines switching on thelight output of the respective luminaire as a response to reception of astatus indication that indicates an occurrence of a given eventpertaining to the particular other luminaire.
 20. A lighting systemaccording to claim 19, wherein the control portion of the lightingsystem control entity is arranged to create the operational dependencyin response to: the relationship strength value for the particular otherluminaire reported with the respective luminaire exceeding a firstthreshold, and the relationship strength value for the respectiveluminaire reported with the particular other luminaire failing to exceeda second threshold that is smaller than the first threshold.